Why won't my TBI 350 run right??

[Powerhouse Ranch]

Getting pretty cranky with this motor right now, getting me cranky with the truck. Been a problem for a while now, only getting worse. I am young, and I need the gurus!

As we all know, the '88 Jimmy (project thread linked below) has been absolutely butchered by the PO, and i'm trying to piece it all together again. When i got it, it didn't run or even start for that matter.

WHAT I'VE DONE:

-Repaired pinched ignition wire, started the truck
-Oil change
-Made sure all motor wiring was plugged in, vacuum lines where they need to be, etc.
-Replaced aftermarket fan with an original from Burb
-Replaced radiator, flushed system
-Replaced oil sender
-Replaced all spark plugs (they were very rough, can take a picture later if necessary)
-Played with timing, not 100% yet
-Running new fuel, with small amount of Berryman's to help clean the fuel lines that sat for years

I believe that's it. . . THE MAIN PROBLEM, whether this is related or not or simply having to do with the throttle, when i'm giving it gas, there's nothing, there's nothing, then all the sudden there's everything! I looked at the throttle cable linkage and all that jazz and compared to Burb and it looked the same, not too knowledgable in this category yet. I need this throttle pedal to be a normal throttle pedal and i need the engine to idle like the happy little small block that it is. If i need to do a video of it running or the throttle thing i'm explaining, just ask. I need to figure this out!

Any tips and tricks are highly appreciated

 

[RoryH19]

Have you tried the temp sensor by the thermostat? Easy replacement and causes many issues if not operating.
Also when you set the timing did you disconnect the advance wire under the brake booster? Then set timing to 0-4 degrees. At least that's where I have mine.
Also can you see a nice spray of gas from the injectors? Does it increase proportional to the throttle when you try to rev the engine?
Not sure if you have duel tanks but do you have the same issue on either side?
Also did you change the fuel filter on the frame rail?
My initial thoughts on potential solutions.

Just remembered, I had an intermittent issue with my pickup coil inside the distributor. Took my forever to isolate.

 

[SirRobyn0]

I'd like a video or at least an audio to hear what it is doing. Thanks.

 

[Powerhouse Ranch]

I'd like a video or at least an audio to hear what it is doing. Thanks.

I'll get one tomorrow, and get a picture of the spark plugs

 

[AyWoSch Motors]

Have you tried the temp sensor by the thermostat? Easy replacement and causes many issues if not operating.
Also when you set the timing did you disconnect the advance wire under the brake booster? Then set timing to 0-4 degrees. At least that's where I have mine.
Also can you see a nice spray of gas from the injectors? Does it increase proportional to the throttle when you try to rev the engine?
Not sure if you have duel tanks but do you have the same issue on either side?
Also did you change the fuel filter on the frame rail?
My initial thoughts on potential solutions.

Just remembered, I had an intermittent issue with my pickup coil inside the distributor. Took my forever to isolate.

Everything he said lol.

All I can think of on top of that, is maybe the injectors are on the Fritz, had that happen to me. And maybe the throttle cable is rusted.
Does sound like the computer is compensating for something. If you dont unplug the advance wire, when timing it, itll screw up everything.

I've had and have many TBI 350s, and many squarebodies, but never any TBI 350 squarebodies. Only ever dealt with one, and that's the most fickle truck ever to get running and keep running, but once you mess with it for like half an hour, itll stay running all day.

 

[SirRobyn0]

I'll get one tomorrow, and get a picture of the spark plugs

Ok thanks. The other guys have all given great ideas, but I think a little video will help make it easier to narrow down.

 

[Powerhouse Ranch]

Here's the video/audio requested. Thanks for all of the ideas above, all will be looked into. And yes, as featured the fuel sprayers are working. Below are also the spark plugs taken out, bottom side is front of block and the left side will be the passenger side. And a flippin belt squeal just started now to add to the mayhem! The "vacuum" sounding leak i believe are the fuel sprayers, as i've determined. The idle does smooth out for a moment before i go under it, that's pretty much the best it does. i'm sure this is all timing related and throttle pedal related, not too experienced in timing so if you feel you must break it down into elementary terms, feel free

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[cstew47]

Getting pretty cranky with this motor right now, getting me cranky with the truck. Been a problem for a while now, only getting worse. I am young, and I need the gurus!

As we all know, the '88 Jimmy (project thread linked below) has been absolutely butchered by the PO, and i'm trying to piece it all together again. When i got it, it didn't run or even start for that matter.

WHAT I'VE DONE:

-Repaired pinched ignition wire, started the truck
-Oil change
-Made sure all motor wiring was plugged in, vacuum lines where they need to be, etc.
-Replaced aftermarket fan with an original from Burb
-Replaced radiator, flushed system
-Replaced oil sender
-Replaced all spark plugs (they were very rough, can take a picture later if necessary)
-Played with timing, not 100% yet
-Running new fuel, with small amount of Berryman's to help clean the fuel lines that sat for years

I believe that's it. . . THE MAIN PROBLEM, whether this is related or not or simply having to do with the throttle, when i'm giving it gas, there's nothing, there's nothing, then all the sudden there's everything! I looked at the throttle cable linkage and all that jazz and compared to Burb and it looked the same, not too knowledgable in this category yet. I need this throttle pedal to be a normal throttle pedal and i need the engine to idle like the happy little small block that it is. If i need to do a video of it running or the throttle thing i'm explaining, just ask. I need to figure this out!

Any tips and tricks are highly appreciated

I didn't see anything about what tranny you have. If it is a 700r4 or 4l60, you could have some issues with the TV cable.

 

[Powerhouse Ranch]

I didn't see anything about what tranny you have. If it is a 700r4 or 4l60, you could have some issues with the TV cable.

Been swapped from auto to manual (PO). It's a Muncie SM465 4-speed w/ granny gear

 

[Bextreme04]

It sounds like you have a few things going on there. It sounds and acts like you have a massive vacuum leak. I would suggest getting a can of something flammable like brake or carb cleaner and spray it around to see if you get a sudden surge in RPM or a smoothing out when you spray a certain area. I would also say that you should check TPS voltage and MAP voltage at idle.

The injector spray pattern wasn't visible in your video and it looked like it was dripping. This usually indicates that you have dirty or clogged up injectors. It should be a fine mist in a cone pattern. This could also be causing the surge

 

[gmbellew]

in addition to the above advice to check for vacuum leaks, making sure all the sensors are hooked up, the timing is 0 degrees with the EST wire unplugged, and that the fuel is fresh I'd spend a few bucks and get a Bluetooth aldl reader and download ALDLDROID and see what the computer sees each sensor is doing. it may save a lot of troubleshooting time. it was hard to see in the video, but I think I saw decent injector spray.

 

[SirRobyn0]

@Powerhouse Ranch, Ok. My two cents. I think but don't know for sure that it's with one of the sensors.

Does the truck have a working check engine light?
Do you have anyway to look at the data stream? If not can you borrow an older friends scanner, has to be able to connect to your ALDL connector not an OBD2 scanner.

Are you sure that the MAP sensor is connected to a manifold vacuum source. Please double check that it is.

I think that there is something preventing the ECU from opening up the pulse width of the injectors when it should.

You could have a dead or bad TPS sensor. Did you have to install a new or used one and if so did you adjust it? If not easiest way is on a scanner set to .40 - .60 volts at closed throttle. TPS needs to give the ECM a steady change in resistance as throttle is increased. Again would need to be checked on a scanner, or you maybe able to look on google to find out what wires to probe to do it with a multi-meter, but I've always done it on a scanner so I'm not much help on how to do it with a multi-meter.

I kind of doubt this is a timing problem, but it wouldn't hurt for you to get it dialed in. You can take note of where you have it set at now with the EST wire disconnected, and then set it to zero and plug the wire back in.

Do check for vacuum leaks, if you have a bad enough leak, not only will it cause vacuum leak symptoms, but it'll mess with the readings for the MAP sensor. Looks like you have a vacuum gauge hooked up. What are the idle readings does it flutter or is the reading is below 15 at idle? When your trying to rev it does the vacuum start to drop some as your opening the throttle?

How is the throttle shaft on the throttle body, is it loose?

another thing you can do. Hook your timing light up, and do this in the garage or somewhere else that isn't to bright. Hook your timing light up this time instead of pointing the light at the timing marks point it at the fuel injector and pull the trigger, the flashing light will cause you eye to see the fuel injector spray pattern in freeze frame. It's actually really cool. You should see a nice cone shaped spray pattern out of each injector with no dripping. I doubt you'll see anything wrong in the spray pattern, what I want you to do is rev it up though that part where it won't go up in RPM. As soon as you crack the throttle you should be able to see an visible increase in the amount of fuel sprayed. You won't be able to see it with your naked eye you got to shine that timing light at it. I suspect you won't see a fuel increase until you get though the part that doesn't want to rev. This would prove it to be a computer issue and not mechanical.

Hopefully something here will help.

 

[SirRobyn0]

I agree vacuum leaks should be tested for but it seem to me that these made quite a bit of that kind of noise and it was air going though the idle air control valve.

 

[Powerhouse Ranch]

@Powerhouse Ranch, Ok. My two cents. I think but don't know for sure that it's with one of the sensors.

Does the truck have a working check engine light?
Do you have anyway to look at the data stream? If not can you borrow an older friends scanner, has to be able to connect to your ALDL connector not an OBD2 scanner.

Are you sure that the MAP sensor is connected to a manifold vacuum source. Please double check that it is.

I think that there is something preventing the ECU from opening up the pulse width of the injectors when it should.

You could have a dead or bad TPS sensor. Did you have to install a new or used one and if so did you adjust it? If not easiest way is on a scanner set to .40 - .60 volts at closed throttle. TPS needs to give the ECM a steady change in resistance as throttle is increased. Again would need to be checked on a scanner, or you maybe able to look on google to find out what wires to probe to do it with a multi-meter, but I've always done it on a scanner so I'm not much help on how to do it with a multi-meter.

I kind of doubt this is a timing problem, but it wouldn't hurt for you to get it dialed in. You can take note of where you have it set at now with the EST wire disconnected, and then set it to zero and plug the wire back in.

Do check for vacuum leaks, if you have a bad enough leak, not only will it cause vacuum leak symptoms, but it'll mess with the readings for the MAP sensor. Looks like you have a vacuum gauge hooked up. What are the idle readings does it flutter or is the reading is below 15 at idle? When your trying to rev it does the vacuum start to drop some as your opening the throttle?

How is the throttle shaft on the throttle body, is it loose?

another thing you can do. Hook your timing light up, and do this in the garage or somewhere else that isn't to bright. Hook your timing light up this time instead of pointing the light at the timing marks point it at the fuel injector and pull the trigger, the flashing light will cause you eye to see the fuel injector spray pattern in freeze frame. It's actually really cool. You should see a nice cone shaped spray pattern out of each injector with no dripping. I doubt you'll see anything wrong in the spray pattern, what I want you to do is rev it up though that part where it won't go up in RPM. As soon as you crack the throttle you should be able to see an visible increase in the amount of fuel sprayed. You won't be able to see it with your naked eye you got to shine that timing light at it. I suspect you won't see a fuel increase until you get though the part that doesn't want to rev. This would prove it to be a computer issue and not mechanical.

Hopefully something here will help.

okay so it does have a working check engine light, which i bought with it on and turned off when i replaced the oxygen sensor. I have replaced the MAP sensor and it is indeed hooked up. I'll have to see whether or not my dad has the hookup for my truck, he's a mechanic of over 30 years and has been helping me along the way, but hard to get ahold of at times. Vacuum leaks, now i said that it may be the injectors spraying, as that's what i'm 99% sure the noise is coming from, does it make such a noise? or is an actual leak nearby that'll need carb cleaner sprayed to check for idle change?

And you're thinking my throttle issue is computer related? would've been my last guess with an '87. Hoped to avoid things like that but i guess i just had to get the dang TBI! haha

Thank you for your words

 

[SirRobyn0]

okay so it does have a working check engine light, which i bought with it on and turned off when i replaced the oxygen sensor. I have replaced the MAP sensor and it is indeed hooked up. I'll have to see whether or not my dad has the hookup for my truck, he's a mechanic of over 30 years and has been helping me along the way, but hard to get ahold of at times. Vacuum leaks, now i said that it may be the injectors spraying, as that's what i'm 99% sure the noise is coming from, does it make such a noise? or is an actual leak nearby that'll need carb cleaner sprayed to check for idle change?

And you're thinking my throttle issue is computer related? would've been my last guess with an '87. Hoped to avoid things like that but i guess i just had to get the dang TBI! haha

Thank you for your words

YW. I just rewatched your video and no I don't think you have a vacuum leak, however it's easy enough to check for.

I think that sound that sounds like vacuum is actually air going past the idle air control valve and is perfectly normal. Still it's worth checking for a leak.

Get the timing set right. I was just rewatching it and it does sound quite a bit retarded.

Try to set it with a light if at all possible. If you don't have a light try to set it for highest vacuum. That's not the best way to do it but should get it to run.

If you can't get the timing set right consider that it might have a very loose timing chain or skipped a tooth. You can take the distributor cap off and turn the engine manually in one direction until you see the ignition rotor move, then turn it the oposite direction, it should only take a few degrees of turning the balancer before you see the rotor turn.

The reason I'm saying all this is in rewatching your video it just sounds like the timing is way retarded.

I guess long story short, the me what you have going on is not a common problem so the testing you perform will be what reveals the problem.

Good luck and let us know if you have questions.